Ball bearing screw jack



Dec.3l, 1940. 1. o. STURM BALL BEARING scR'Ew JACK Filed Oct. 11, 1958 v 1 Q I I.) A

L. D $TURM 15% 'TTURA/E/ Patented Dec. 31, 1940 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates generally to screw Jacks, and particularly to a ball bearing screw jack especially adapted for use in connection with elevators.

5 The main object of this invention is to construct a screw jack in which the friction is reduced to a minimum.

The second object is to construct a screw jack which will be especially adapted for use in con-' nection with elevators, automobile hoists and similar contrivances.

The third object is to construct .a jack in which the power requirements will be held to a minimum.

5 These and other objects are accomplished in the manner set forth in the following specification as illustrated in the accompanying drawing,

in which:

Fig. 1 is a side elevation of the device showing 20 its application to a lift and showing the foundation broken away in section.

Fig. 2 is an enlarged section taken along the line 22 in Fig. 1.

Fig. 3 is a transverse section taken along the 35 line 3-3 in Fig. 2.

Fig. 4 is a transverse section taken alon the line 4-4 in F18. 2.

Fig. 5 is a section taken along the line 5-5 in Fig. 3.

Similar numerals refer to similar parts throughout the several views.

Referring in detail to the drawing, there is shown a base It upon which is formed a cylindrical housing II in the upper end of which is 35 placed an anti-friction bearing l2. Through the bearing l2 extends the sleeve l3 of the rotatable nut I 4 which is provided with the spiral groove i5 which conforms in shape to the spiral groove it formed within the screw ll whose upper end is attached to the lift l8 which slides between the guides l9. Spherical ball bearings 20 occupy the groove and the adjacent portion of the'groove IS. A cap i2-A covers the bearing I2.

5 A channel 2| is formed in the outer surface 22 of the nut l4 and communicates between the uppermost and lowermost portions of the ball bearing portions of the grooves l5 and IS.

A deflector 23 is secured within the nut H 50 and its purpose is to steer the ball bearings p out of the spiral groove into the channel 2|. A sleeve 24 covers the nut l4 and forms a closure for the channel 2|.

The bearing i2 is a combined radial and thrust bearing and takes the actual load in a vertical direction. On the sleeve I3 are secured the nuts 25 above the belt pulley 26 which is driven through the belt 2'! from the pulley 28, which in turn is 5 operated by the motor 29 which is mounted on thebracket 30 of the housing II.

It will be understood that the screw ll is confined within the tube 3| and extends downwardly from the housing ll into the floor 32.

In the operation of the device when it is desired to raise the lift it], the motor 29 is operated in a suitable direction. Through the belt 21, the pulley 26 is rotated correspondingly and since it is secured to the sleeve I3 by means of 15 the key 33, it follows that the nut r4 must also rotate. Since the ball bearings 20 can travel around the groove i5 and back to the point of beginning, it follows that all of the end thrust exerted against the screw I! will be transmitted in the proper direction, and since the pulley 26 is secured to the sleeve I 3 by means of the key 33, it follows that the nut I4 is correspondingly rotated and the screw ll raised or lowered as desired. 25

By the use of this device a large portion of the usual friction losses is eliminated and an exceedingly free running jack is produced.

I claim:

A screw jack having a lift, for said lift, a base disposed under said lift, an upright housing mounted on said base, an antifriction bearing disposed at the top of said housing and having a vertical axis, a rotatable nut suspended from said bearing within said housing, said nut having a central opening formed therein provided with a helical groove the opposite ends of which are joined by a channel formed in the exterior of the nut, a cylindrical sleeve disposed around said nut forming a cover for said channel, a plurality of ball bearings occupying said groove and channel, the balls in the groove projecting into the nut openings to form an antifriction thread, a non-=rotatable vertical load supporting screw passing through said nut and having a spiral groove formed around same into which said balls project, the upper end of said screw being attached to said lift and means for rotating said nut, said screw projecting above and below said base at all times.

an upright guide 0 LEWIS D. STURM. 

